This invention relates to systems and methods for providing enlargement or reduction functions in a photocopy device of the type creating reproduced image by selectively defining rows and columns of picture elements.
The complex nature of contemporary society has created a need for an economical means to quickly reproduce printed materials. This need has been filled by numerous copy machines with the dry paper copier foremost in the field. With the advent of these machines, there has been a widespread growth in the manipulation, transmission and recordation of image data in a wide variety of forms. For a great many applications, the extremely high resolutions achievable with photographic films and other continuous tone media are not needed and copiers of low resolution utilizing digital imaging techniques or line scanning techniques have proved to generate acceptable copy quality at a lower unit cost. In these latter systems, a line resolution in the order of 0.1 mm is generally acceptable and capable of producing photographic grey scale, half tone and line images as well as alpha-numeric characters, graphical information and the like.
It is often desirable during copying to change the size of an image by enlargement or reduction within a range of an order of magnitude and sometimes more. The means currently known for effecting such changes are not amenable to a wide range of scale variations and seldom permit precise selection of scale factors without tedious and complex adjustments. The known systems also tend to be excessively cumbersome and costly. An image may be enlarged or reduced by an optical system but normally a system capable of reduction is not readily suitable for enlargement and vice versa. In addition, in either type of optical system, enlargements or reductions are usually available only in a limited range due to optical considerations and when a relatively broad scale factor change is required, the optical systems become inordinately complex.
An important desirable feature for such systems is that the image recording device should be a conventional and reliable system that need not be adjusted or manipulated to give different dot sizes for different image magnification or reduction ratios. While a reduction in dot size could give higher resolution on a reduced image, the complexity and greater degree of precision necessarily required with such a system would not be desirable for the great majority of applications. Known recording techniques for producing hard copy, such as dot matrix printers, are highly reliable and operate at high rates of speed, but essentially do not permit introduction of a change in dot size. This is true whether one considers an ink jet printer, electrostatic printer, impact printer or thermal printer. One of these devices can be chosen for a given image resolution in the final copy, but what is most important in many instances is to be able to immediately obtain a reproduced image of desired size that has reasonable fidelity to the original which itself need not be of high quality.
The patent to Suga U.S. Pat. No. 4,090,188 discloses a dot matrix converter. The patent directs itself to the solution of the problem of enlarging Chinese characters. Thus the printer is arranged to enlarge a Chinese character from a dot matrix of smaller size. To this end a new row and a new column are added to the original dot matrix. However opposed bits in the rows or columns are compared with each other. As a result the new character does not exactly resemble the smaller original character. Hence, a complicated comparison between adjacent dots of the original pattern must be effected.